Permission denied error while copying the files to another user directory using WINSCP?

I have a few folder in one of my ubuntu machine in the directory /export/home/ as -

user1user2user3

Whenever any user login to that machine, it always takes him to that directory as a default. If I am user1, and I am logging in to that machine, then after logging, if I do pwd, I always see -

/export/home/user1

Now what I am supposed to do is, I have opened a winscp on my desktop as user1 to connect to that machine, and then I need to copy a file from my desktop to user2 folder but whenever I try to open user2 folder in winscp, it always gives me -

Permission denied error..

Is there any way, I can ask user2 to give me permission (by logging into his account from putty) to copy the files using winscp from my desktop to user2 folder?